DOPED PEROVSKITE BARIUM STANNATE MATERIAL WITH PREPARATION METHOD AND APPLICATION THEREOF

Abstract

Disclosed herein is a doped perovskite barium stannate material, which has a chemical general formula of BaA.sub.xB.sub.xSn.sub.1-2xO.sub.3, where A is at least one of In, Y, Bi and La; B is at least one of Nb and Ta, and 0<x≤0.025. The doped perovskite barium stannate material disclosed in the invention has a high dielectric constant, low dielectric loss and good temperature-stability, and it can be used not only as low-frequency ceramic capacitor dielectrics, but also as microwave dielectric ceramics because of its excellent microwave dielectric properties, implying the potential application in the field of microwave communication. What's more, disclosed is a method to prepare the doped perovskite barium stannate material and the application of the doped perovskite barium stannate material in a low-frequency ceramic capacitor or microwave communication dielectric ceramics.

Claims

1. A doped perovskite barium stannate material, wherein the doped perovskite barium stannate material has a chemical general formula:
BaA.sub.xB.sub.xSn.sub.1-2xO.sub.3, where A is In, Y, Bi, or La, or a mixture of two or more of these; B is Nb or Ta, or a mixture of both; and 0<x≤0.025.

2. A preparation method of a doped perovskite barium stannate material of claim 1, wherein the preparation method comprises of the following steps: (1) Weighing out a barium source, a tetravalent tin source, an A.sup.3+ source and a B.sup.5+ source, respectively, according to the chemical general formula; (2) Mixing the above sources thoroughly and ball-milling, and then drying to obtain homogeneous mixed powder; (3) Placing the mixed powder obtained in step (2) into an alumina crucible, and performing calcination treatment on the mixed powder to obtain calcined powder; (4) Adding sintering aid, B.sub.2O.sub.3, to the calcined powder, and then ball-milling again and drying to obtain preliminary powder; and (5) Pressing the preliminary powder obtained in step (4) to get pellets, followed by sintering the pellets to obtain the doped perovskite barium stannate material.

3. The preparation method of a doped perovskite barium stannate material of claim 2, wherein at least one of the following requirements (a) to (d) is satisfied: (a) The barium source is BaCO.sub.3, Ba(NO.sub.3).sub.2, Ba(NO.sub.3).sub.2 hydrates, BaSO.sub.4, BaSO.sub.4 hydrates, Ba(OH).sub.2, Ba(OH).sub.2 hydrates, Ba(C.sub.2H.sub.3O.sub.2).sub.2, Ba(C.sub.2H.sub.3O.sub.2).sub.2 hydrates, Ba.sub.3(PO.sub.4).sub.2, or Ba.sub.3(PO.sub.4).sub.2 hydrates, or a mixture of two or more of these; (b) The tin source is SnO.sub.2; (c) The A.sup.3+ source is A.sub.2O.sub.3, A.sub.2(C.sub.2O.sub.4).sub.3, A.sub.2(C.sub.2O.sub.4).sub.3 hydrates, A(NO.sub.3).sub.3, A(NO.sub.3).sub.3 hydrates, A.sub.2(SO.sub.4).sub.3, A.sub.2(SO.sub.4).sub.3 hydrates, A.sub.2(CO.sub.3).sub.3, A.sub.2(CO.sub.3).sub.3 hydrates, A(C.sub.2H.sub.3O.sub.2).sub.3, or A(C.sub.2H.sub.3O.sub.2).sub.3 hydrates, or a mixture of two or more of these; and (d) The B.sup.5+ source is B.sub.2O.sub.5.

4. The preparation method of a doped perovskite barium stannate material of claim 2, wherein in step (3), the calcination treatment comprises of heating up to a temperature in a range from 1000° C. to 1200° C. for 3 hours with a heating rate of 4° C./min to 6° C./min, and naturally cooling down to room temperature.

5. The preparation method of a doped perovskite barium stannate material of claim 2, wherein in step (4), a weight ratio of the sintering aid, B.sub.2O.sub.3, to the calcined powder is 0.5% to 5%.

6. The preparation method of a doped perovskite barium stannate material of claim 2, wherein the preparation method further comprises of step (6) after step (5): performing surface polishing treatment on the doped perovskite barium stannate material obtained in step (5) and then annealing.

7. The preparation method of a doped perovskite barium stannate material of claim 6, wherein the annealing comprises of heating up to a temperature in a range from 1000° C. to 1500° C. for 1 to 24 hours in air with a heating rate of 1.5° C./min to 15° C./min, and then naturally cooling down to room temperature.

8. The preparation method of a doped perovskite barium stannate material of claim 2, wherein in step (5), the sintering comprises of heating up to a temperature in a range from 1300° C. to 1500° C. for 6 to 24 hours in air with a heating rate of 4° C./min to 6° C./min, and then naturally cooling down to room temperature.

9. The preparation method of a doped perovskite barium stannate material of claim 2, wherein in step (3) and step (4), the ball-milling is carried out for at least 12 hours with yttrium-stabilized zirconia beads as a medium and ethanol and/or acetone as solution.

10. A low-frequency ceramic capacitor or microwave communication dielectric ceramics made of a doped perovskite barium stannate material of claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 shows XRD spectra of (A.sup.3++B.sup.5+) co-doped perovskite barium stannate materials prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903), Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803), Example 3 (BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503), and Example 4 (BaLa.sub.0.001Ta.sub.0.001Sn.sub.0.99803), as well as an un-doped perovskite barium stannate material prepared in Comparative Example 1 (BaSnO.sub.3);

[0031] FIGS. 2a-2c are backscattered electron (BSE) images of (La+Nb) co-doped perovskite barium stannate materials prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903), Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803), and Example 3(BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503), and FIGS. 2d-2f are corresponding secondary electron (SE) images of (La+Nb) co-doped perovskite barium stannate materials prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903), Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803), and Example 3 (BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503);

[0032] FIG. 3 shows the frequency-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903), which were measured at room temperature;

[0033] FIG. 4 shows the temperature-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903) with four selected frequencies (100 Hz, 1 kHz, 10 kHz and 100 kHz);

[0034] FIG. 5 shows the frequency-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803), which were measured at room temperature;

[0035] FIG. 6 shows the temperature-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803) with four selected frequencies (100 Hz, 1 kHz, 10 kHz and 100 kHz);

[0036] FIG. 7 shows the frequency-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 3 (BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503), which were measured at room temperature;

[0037] FIG. 8 shows the frequency-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 4 (BaLa.sub.0.001Ta.sub.0.001Sn.sub.0.998O.sub.3), which were measured at room temperature; and

[0038] FIG. 9 shows the frequency-dependent dielectric properties of an un-doped perovskite barium stannate material prepared in Comparative Example 1 (BaSnO.sub.3), which were measured at room temperature.

DETAILED DESCRIPTION

[0039] Hereafter, the invention will be further described in conjunction with specific examples in order to better illustrate objectives, technical solutions and advantages.

Example 1

[0040] A doped perovskite barium stannate material in Example 1 has a chemical general formula: BaA.sub.xB.sub.xSn.sub.1-2xO.sub.3, where A=La, B=Nb, x is an atomic ratio and x=0.0005. The doped perovskite barium stannate material is prepared through the following steps:

[0041] (1) According to the chemical general formula, weighing out 19.7340 g BaCO.sub.3 reactant powder, 15.0559 g SnO.sub.2 reactant powder, 0.0082 g La.sub.2O.sub.3 reactant powder and 0.0066 g Nb.sub.2O.sub.5 reactant powder, respectively;

[0042] (2) Placing the abovementioned reactant powders into a ball milling tank, and ball-milling for 12 hours with ethanol as solution and yttrium-stabilized zirconia beads as a ball-milling medium, then mixing uniformly and drying to get homogeneous mixed powder;

[0043] (3) Placing the mixed powder obtained in step (2) into an alumina crucible for calcination treatment, in particular, carrying out the calcination treatment at 1,000° C. for 3 hours in air with the heating rate of 5° C./min , and then naturally cooling down to room temperature;

[0044] (4) After the calcination treatment, adding 2.5 wt. % B.sub.2O.sub.3 into the mixed powder, and then performing ball-milling again under the same conditions as that of step (2) and drying to get preliminary powder; and

[0045] (5) Placing the preliminary powder obtained in step (4) into a die, pressing under a pressure of 1 MPa to get green pellets, and then sintering the green pellets at 1,350° C. for 12 hours in air with the heating rate of 5° C./min, and then naturally cooling down to room temperature to get a dense doped perovskite barium stannate material.

[0046] Example 2

[0047] A doped perovskite barium stannate material in Example 2 has a chemical general formula: BaA.sub.xB.sub.xSn.sub.1-2xO.sub.3, where A=La, B=Nb, x is an atomic ratio and x=0.001. The doped perovskite barium stannate material is prepared through the following steps:

[0048] (1) According to the chemical general formula, weighing out 19.7340 g BaCO.sub.3 reactant powder, 15.0409 g SnO.sub.2 reactant powder, 0.0163 g La.sub.2O.sub.3 reactant powder and 0.0133 g Nb.sub.2O.sub.5 reactant powder, respectively;

[0049] (2) Placing the above-mentioned reactant powders into a ball milling tank, and ball-milling for 12 hours with ethanol as solution and yttrium-stabilized zirconia beads as a ball-milling medium, then mixing uniformly and drying to give homogeneous mixed powder;

[0050] (3) Placing the mixed powder obtained in step (2) into an alumina crucible for calcination treatment, in particular, carrying out the calcination treatment at 1,000° C. for 3 hours in air with the heating rate of 5° C./min, and then naturally cooling down to room temperature;

[0051] (4) After the calcination treatment, adding 2.5 wt. % B.sub.2O.sub.3 into the mixed powder, and then performing ball-milling again under the same conditions as that of step (2) and drying to get preliminary powder; and

[0052] (5) Placing the preliminary powder obtained in step (4) into a die, pressing under a pressure of 1 MPa to get green pellets, and then sintering the green pellets at 1,350° C. for 12 hours in air with the heating rate of 5° C./min, and then naturally cooling down to room temperature to get a dense doped perovskite barium stannate material.

[0053] Example 3

[0054] A doped perovskite barium stannate material in Example 3 has a chemical general formula: BaA.sub.xB.sub.xSn.sub.1-2xO.sub.3, where A=La, B=Nb, x is an atomic ratio and x=0.025. The doped perovskite barium stannate material is prepared through the following steps:

[0055] (1) According to the chemical general formula, weighing out 19.7340 g BaCO.sub.3 reactant powder, 14.3145 g SnO.sub.2 reactant powder, 0.4073 g La.sub.2O.sub.3 reactant powder and 0.3323 g Nb.sub.2O.sub.5 reactant powder, respectively;

[0056] (2) Placing the above-mentioned reactant powders into a ball milling tank, and ball-milling for 12 hours with ethanol as solution and yttrium-stabilized zirconia beads as a ball-milling medium, then mixing uniformly and drying to get homogeneous mixed powder;

[0057] (3) Placing the mixed powder obtained in step (2) into an alumina crucible for calcination treatment, in particular, carrying out the calcination treatment at 1,000° C. for 3 hours in air with the heating rate of 5° C./min, and naturally cooling down to room temperature;

[0058] (4) After the calcination treatment, adding 0.5 wt. % B.sub.2O.sub.3 into the mixed powder, and then performing ball-milling again under the same conditions as that of step (2) and drying to get preliminary powder;

[0059] (5) Placing the preliminary powder obtained in step (4) into a die, pressing under a pressure of 1 MPa to get green pellets, and then sintering the green pellets at 1,500° C. for 6 hours in air with the heating rate of 5° C./min, and then naturally cooling down to room temperature to get dense doped perovskite barium stannate ceramic pellets; and

[0060] (6) Performing surface polishing on the ceramic pellets obtained in step (5), and then annealing to obtain the doped perovskite barium stannate material; the surface polishing treatment includes rough polishing with 240-mesh sandpaper and then fine polishing with 1200-mesh sandpaper; and the annealing is carried out at 1,300° C. for 1 hour in air with the heating rate of 5° C./min.

[0061] Example 4

[0062] A doped perovskite barium stannate material in Example 4 has a chemical general formula: BaA.sub.xB.sub.xSn.sub.1-2xO.sub.3, where A=La, B=Ta, x is the atomic ratio and x=0.001. The doped perovskite barium stannate material is prepared through the following steps:

[0063] (1) According to the chemical general formula, weighing out 19.7340 g BaCO.sub.3 reactant powder, 15.0409 g SnO.sub.2 reactant powder, 0.0163 g La.sub.2O.sub.3 reactant powder and 0.0221 g Ta.sub.2O.sub.5 reactant powder, respectively;

[0064] (2) Placing the above-mentioned reactant powders into a ball milling tank, and ball-milling for 12 hours with ethanol as solution and yttrium-stabilized zirconia beads as a ball-milling medium, then mixing uniformly and drying to get homogeneous mixed powder;

[0065] (3) Placing the mixed powder obtained in step (2) into an alumina crucible for calcination treatment, in particular, carrying out the calcination treatment at 1,000° C. for 3 hours in air with the heating rate of 5° C./min;

[0066] (4) After the calcination treatment, adding 2.5 wt. % B.sub.2O.sub.3 into the mixed powder, and then performing ball-milling again under the same conditions as that of step (2) and drying to get preliminary powder; and

[0067] (5) Placing the preliminary powder obtained in step (4) into a die, pressing under a pressure of 1 MPa to get green pellets, and then sintering the green pellets at 1,500° C. for 24 hours in air with the heating rate of 5° C./min, and then naturally cooling down to room temperature to get a dense doped perovskite barium stannate material.

[0068] Comparative Example 1

[0069] In the comparative example, BaSnO.sub.3 is prepared through the following steps:

[0070] (1) According to the chemical general formula BaSnO.sub.3, weighing out 19.7340 g BaCO.sub.3 reactant powder and 15.071 g SnO.sub.2 reactant powder, respectively;

[0071] (2) Placing the above-mentioned reactant powders into a ball milling tank, and ball-milling for 12 hours with ethanol as solution and yttrium-stabilized zirconia beads as ball-milling medium, then mixing uniformly and drying to get homogeneous mixed powder;

[0072] (3) Placing the mixed powder obtained in step (2) into an alumina crucible for calcination treatment, in particular, carrying out the calcination treatment at 1,200° C. for 3 hours in air with the heating rate of 5° C./min, and naturally cooling down to room temperature;

[0073] (4) After the calcination treatment, adding 5 wt. % B.sub.2O.sub.3 into the mixed powder, and then performing ball-milling again under the same conditions as that of step (2) and drying to get preliminary powder; and

[0074] (5) Placing the preliminary powder obtained in step (4) into a die, pressing under a pressure of 1 MPa to get green pellets, and then sintering the green pellets at 1,450° C. for 12 hours in air with the heating rate of 5° C./min, and then naturally cooling down to room temperature to get a dense doped perovskite barium stannate material.

[0075] FIG. 1 shows XRD spectra of (A.sup.3++B.sup.5+) co-doped perovskite barium stannate materials prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903), Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803), Example 3 (BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503), and Example 4 (BaLa.sub.0.001Ta.sub.0.001Sn.sub.0.99803), as well as an un-doped perovskite barium stannate material prepared in Comparative Example 1 (BaSnO.sub.3). FIG. 1 shows that the (A.sup.3++B.sup.5+) co-doped perovskite barium stannate materials prepared in Examples 1 to 4 and the un-doped perovskite barium stannate material prepared in Comparative Example 1 (BaSnO.sub.3) have the same cubic perovskite structure, and all are single phase.

[0076] FIGS. 2a-2c are backscattered electron (BSE) images and secondary electron (SE) images of (La+Nb) co-doped perovskite barium stannate materials prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903), Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803), and Example 3 (BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503); and FIGS. 2d-2f are corresponding secondary electron (SE) images of (La+Nb) co-doped perovskite barium stannate materials prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903), Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803), and Example 3 (BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503). FIGS. 2a-2f further prove that the (La+Nb) co-doped perovskite barium stannate materials prepared in Examples 1 to 3 are single-phase and contain no impurities.

[0077] FIG. 3 shows the frequency-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903), which were measured at room temperature. FIG. 3 implies that the (La+Nb) co-doped perovskite barium stannate material prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903) has a dielectric constant in a range from 1.6×10.sup.3 to 3×10.sup.3 at a frequency range of 20 Hz to 1 GHz, and has dielectric loss less than 1% at frequency range of 0.2 MHz to 25 MHz.

[0078] FIG. 4 shows the temperature-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903) with four selected frequencies (100 Hz, 1 kHz, 10 kHz and 100 kHz). FIG. 4 implies that the (La+Nb) co-doped perovskite barium stannate material prepared in Example 1 (BaLa.sub.0.0005Nb.sub.0.0005Sn.sub.0.99903) has a dielectric constant in a range from 1.2×10.sup.3 to 3×10.sup.3, which is temperature independent at the temperature range of 10 K to 450 K, and its dielectric loss is less than 5% below 300 K.

[0079] FIG. 5 shows the frequency-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803), which were measured at room temperature. FIG. 5 implies that the (La+Nb) co-doped perovskite barium stannate material prepared in Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803) has a dielectric constant in a range from 3.5×10.sup.3 to 5×10.sup.3 at a frequency range of 20 Hz to 1 GHz, and its dielectric loss is less than 4% o after 1 MHz, and less than 0.5%o after 300 MHz.

[0080] FIG. 6 shows the temperature-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803) with four selected frequencies (100 Hz, 1 kHz, 10 kHz and 100 kHz). FIG. 6 implies that the (La+Nb) co-doped perovskite barium stannate material prepared in Example 2 (BaLa.sub.0.001Nb.sub.0.001Sn.sub.0.99803) has a dielectric constant in a range from 3.6×10.sup.3 to 4.8×10.sup.3, which is temperature independent from 10 K to 450 K, and its dielectric loss depends on temperature a little.

[0081] FIG. 7 shows the frequency-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 3 (BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503), which were measured at room temperature. FIG. 7 implies that the (La+Nb) co-doped perovskite barium stannate material prepared in Example 3 (BaLa.sub.0.025Nb.sub.0.025Sn.sub.0.9503) has a dielectric constant in a range from 1.8×10.sup.4 to 8×10.sup.3 at the frequency range of 20 Hz to 2 MHz, and its dielectric loss decreases from 3 to 8% when the frequency increases from 20 Hz to 1.2×10.sup.4 Hz, and the dielectric loss gradually increases to 30% as frequency continues to increase.

[0082] FIG. 8 shows the frequency-dependent dielectric properties of a (La+Nb) co-doped perovskite barium stannate material prepared in Example 4 (BaLa.sub.0.001Ta.sub.0.001Sn.sub.0.99803), which were measured at room temperature. FIG. 8 implies that the (La+Ta) co-doped perovskite barium stannate material prepared in Example 4 (BaLa.sub.0.001Ta.sub.0.001Sn.sub.0.99803) has a dielectric constant in a range from 4×10.sup.3 to 5.6×10.sup.3 at the frequency range of 20 Hz to 2 MHz, and its dielectric loss decreases from 20% to 2.7% o as the frequency increases.

[0083] FIG. 9 shows the frequency-dependent dielectric properties of an un-doped perovskite barium stannate material prepared in Comparative Example 1 (BaSnO.sub.3), which were measured at room temperature. FIG. 9 implies that the un-doped perovskite barium stannate material prepared in Comparative Example 1 (BaSnO.sub.3) has a dielectric constant of 15 at the frequency range of 20 Hz to 1 GHz, and its dielectric loss decreases from 20% to 0.05% as the frequency increases.

[0084] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the invention and are not intended to limit the protection scope of the invention. Although the invention has been described in detail with references to the preferred examples, those of ordinary skill in this field should understand that, the technical solution of the invention can be modified or equivalently replaced without deviating from the essence and scope of the technical solution of the invention.