The present disclosure generally relates to compositions comprising substrate-free 2D tellurene crystals, and the method of making and using the substrate-free 2D tellurene crystals. The 2D tellurene crystals of the present disclosure are characterized by an X-ray diffraction pattern (CuKα radiation, λ=1.54056 A) comprising a peak at 23.79 (2θ±0.1°) and optionally one or more peaks selected from the group consisting of 41.26, 47.79, 50.41, and 64.43 (2θ±0.1°).

A nonlinear optical crystal of guanidinium tetrafluoroborate has a chemical formula of [C(NH.sub.2).sub.3]BF.sub.4 and a molecular weight of 146.89, belongs to the trigonal crystal system, has a space group of R3m; has lattice parameters of a=7.4634(10)Å, b=7.4634(10)Å, c=9.1216(19) (6)Å, and Z=3; has an ultraviolet cutoff edge of 200 nm; and has a frequency-multiplication response that is 4-5 times that of the commercialized nonlinear optical crystal KDP. A hydrothermal method, a room-temperature solution method, an evaporation method or a solvothermal method is used to grow the crystal in a centimeter-scaled size. The crystal can produce frequency-doubling, frequency-tripling, frequency-quadrupling, frequency-quintupling or frequency-sextupling harmonic light output from the fundamental frequency light of 1064 nm generated by a Nd:YAG laser, and/or can produce ultraviolet and deep-ultraviolet frequency-multiplication light output below 200 nm.

A nonlinear optical crystal of guanidinium tetrafluoroborate has a chemical formula of [C(NH.sub.2).sub.3]BF.sub.4 and a molecular weight of 146.89, belongs to the trigonal crystal system, has a space group of R3m; has lattice parameters of a=7.4634(10)Å, b=7.4634(10)Å, c=9.1216(19) (6)Å, and Z=3; has an ultraviolet cutoff edge of 200 nm; and has a frequency-multiplication response that is 4-5 times that of the commercialized nonlinear optical crystal KDP. A hydrothermal method, a room-temperature solution method, an evaporation method or a solvothermal method is used to grow the crystal in a centimeter-scaled size. The crystal can produce frequency-doubling, frequency-tripling, frequency-quadrupling, frequency-quintupling or frequency-sextupling harmonic light output from the fundamental frequency light of 1064 nm generated by a Nd:YAG laser, and/or can produce ultraviolet and deep-ultraviolet frequency-multiplication light output below 200 nm.

A PCSS comprises a photoconductive semiconductor block that exhibits electrically-conductive behavior when exposed to light of a predetermined wavelength; two or more electrodes fixed to the photoconductive semiconductor block and connectable to a power supply; a resonance cavity enveloping the photoconductive semiconductor block, the resonance cavity having a reflective outer surface to trap light within the resonance cavity and the photoconductive semiconductor block, the resonance cavity having a window through the reflective outer surface to admit light of the predetermined wavelength, the resonance cavity being transmissive to light of the predetermined wavelength within the reflective outer surface; and a light source directed toward the photoconductive semiconductor block and through the window, and emitting light at the predetermined wavelength. The photoconductive semiconductor block may include Si, GaAs, GaN, AlN, SiC, and/or Ga.sub.2O.sub.3. The resonance cavity may include glass, crystal, Au, Ag, Cr, Ni, V, Pd, Pt, Ir, Rh, and/or Al.

A PCSS comprises a photoconductive semiconductor block that exhibits electrically-conductive behavior when exposed to light of a predetermined wavelength; two or more electrodes fixed to the photoconductive semiconductor block and connectable to a power supply; a resonance cavity enveloping the photoconductive semiconductor block, the resonance cavity having a reflective outer surface to trap light within the resonance cavity and the photoconductive semiconductor block, the resonance cavity having a window through the reflective outer surface to admit light of the predetermined wavelength, the resonance cavity being transmissive to light of the predetermined wavelength within the reflective outer surface; and a light source directed toward the photoconductive semiconductor block and through the window, and emitting light at the predetermined wavelength. The photoconductive semiconductor block may include Si, GaAs, GaN, AlN, SiC, and/or Ga.sub.2O.sub.3. The resonance cavity may include glass, crystal, Au, Ag, Cr, Ni, V, Pd, Pt, Ir, Rh, and/or Al.

A nanostructure is made of a plurality of nanocrystals on at least one surface or surface region of a titanium body. A method for generating such nanostructure is by means of hydrothermal oxidation. Thereby, the nanocrystals have a basic tetragonal-pyramidal shape, at least in some regions. The area density of the nanocrystals is between 40 and 400 per μm.sup.2, wherein the area density decreases with increasing crystal height. The average spacing of 50 to 160 nm of adjacent nanocrystals is obtained at a nanocrystal height of 23 to 100 nm. This provides a titanium-based, bactericidal and hydrophilic nanostructure for implant surfaces and, at the same time, a corresponding manufacturing method with which the size and distribution of the nanocrystals forming a nanostructure that facilitates healing can be determined.

A method may include stretching a deformable bounding element into a stretched state. The method may further include coating the deformable bounding element with at least one layer of an anti-reflective material while the deformable bounding element is in the stretched state and assembling an optical lens assembly including the deformable bounding element, such that the optical lens assembly adjusts at least one optical property by controlling a shape of the deformable bounding element. The deformable bounding element may have less tension when in a neutral state than the deformable bounding element has when in the stretched state. The method may additionally include coating the deformable bounding element with at least one layer of an anti-reflective material while the deformable bounding element is not in a stretched state. Various other apparatuses, systems, and methods are also disclosed.

A method for growing a GaN crystal suitable as a material of GaN substrates including C-plane GaN substrates includes: a first step of preparing a GaN seed having a nitrogen polar surface; a second step of arranging a pattern mask on the nitrogen polar surface of the GaN seed, the pattern mask being provided with a periodical opening pattern comprising linear openings and including intersections, the pattern mask being arranged such that longitudinal directions of at least part of the linear openings are within ±3° from a direction of an intersection line between the nitrogen polar surface and an M-plane; and a third step of ammonothermally growing a GaN crystal through the pattern mask such that a gap is formed between the GaN crystal and the pattern mask.

A method for growing a GaN crystal suitable as a material of GaN substrates including C-plane GaN substrates includes: a first step of preparing a GaN seed having a nitrogen polar surface; a second step of arranging a pattern mask on the nitrogen polar surface of the GaN seed, the pattern mask being provided with a periodical opening pattern comprising linear openings and including intersections, the pattern mask being arranged such that longitudinal directions of at least part of the linear openings are within ±3° from a direction of an intersection line between the nitrogen polar surface and an M-plane; and a third step of ammonothermally growing a GaN crystal through the pattern mask such that a gap is formed between the GaN crystal and the pattern mask.

The invention provides a battery material comprising-monocrystalline particles not having internal void fractions, wherein each of the monocrystalline particles is without internal grain boundaries such that anisotropic volume change issues of polycrystalline particles don't occur when the particles are charged and discharged during cycling. Also provided is the monocrystalline particles with less-lithium on the particle surface. Also provided is a method for preparing monocrystalline battery material, wherein the battery material may be incorporated into a secondary battery.