A magnetostrictive material includes a FeGaBa alloy that is represented by Expression (1),

Fe.sub.(100-x-y)Ga.sub.xBa.sub.y(1) (in Expression (1), x and y are respectively a content rate (at. %) of Ga and a content rate (at. %) of Ba, and satisfy that y0.012x0.168, y0.05x+1.01, and y0.04/7x+0.87/7).

A magnetostrictive material includes a FeGaSm alloy that is represented by Expression (1),

Fe.sub.(100-x-y)Ga.sub.xSm.sub.y(1) (in Expression (1), x and y are respectively a content rate (at. %) of Ga and a content rate (at. %) of Sm, and satisfy that y0.35x4.2, yx+20.1, and y0.1x+2.1).

A magnetostrictive material includes a FeGaC alloy that is represented by Expression (1),

F.sub.(100-x-y)Ga.sub.xC.sub.y(1) (in Expression (1), x and y are respectively a content rate (at. %) of Ga and a content rate (at. %) of C, and satisfy that y0.5x7.75, yx+20, and y0.5).

A perforating gun includes a charge tube having shaped charges affixed thereto. Each shaped charge includes a radially outward pointing post adapted to receive a detonator cord. A retention member installed on the post provides a compressive force that energetically couples the detonator cord to the post. The radially outermost portion of the retention member is radially flush with or radially recessed relative to the radially outermost portion of each post. In one embodiment, the retention member has a rounded medial portion, a central opening and a pair of locking tabs that point radially inward to the central opening. Each post may include a slot for receiving the detonator cord and a circumferential groove that is adapted to receive the locking tabs.

Compact and power efficient acoustically actuated magnetoelectric antennas for transmitting and receiving very low frequency (VLF) electromagnetic waves utilize magnetoelectric coupling in a magnetic/piezoelectric heterostructure to provide voltage control of magnetization in transmission mode and magnetic control of electric polarization in receiving mode. The magnetoelectric antennas provide a power efficiency enhanced by orders of magnitude compared to magnetically or mechanically switching the magnetization. The antennas can be used in groups or arrays and can be combined to form VLF communication systems.

A downhole acoustic emitter including a support housing with a cavity and ports, in which housing are disposed a rod-type magnetostrictive transducer with an electrical coil on the rods, and an acoustic waveguide in the form of a cylinder which transitions into a tapering cone. The cylindrical portion of the acoustic waveguide is disposed inside the support housing, and the conical portion is disposed outside the housing. The upper end surface of the acoustic waveguide is coaxially joined to the lower emitting surface of the magnetostrictive transducer by soldering, and the acoustic waveguide is joined at its middle portion, which coincides with the zero vibration point of the waveguide, to the support housing by a threaded joint. The downhole acoustic emitter is provided with an emitting element, the upper end of which is coaxially joined to the lower end of the acoustic waveguide by a threaded joint. The magnetostrictive transducer has a length of 200-280 mm and is made of Permendur, and the ports are arranged around the perimeter of the support housing in two rows, the first of which is level with the top turns of the electrical coil of the magnetostrictive transducer, and the second row is level with the bottom turns of the coil. The emitting element is in the form of a cylinder or a prism with a square cross-section.

An apparatus is provided which comprises: a ferromagnetic (FM) region with magnetostrictive (MS) property; a piezo-electric (PZe) region adjacent to the FM region; and a magnetoelectric region adjacent to the FM region. An apparatus is provided which comprises: a FM region with MS property; a PZe region adjacent to the FM region; and a magnetoelectric region, wherein the FM region is at least partially adjacent to the magnetoelectric region. An apparatus is provided which comprises: a FM region with MS property; a PZe region adjacent to the FM region; a magnetoelectric region being adjacent to the FM and PZe regions; a first electrode adjacent to the FM and PZe regions; a second electrode adjacent to the magnetoelectric region; a spin orbit coupling (SOC) region adjacent to the magnetoelectric region; and a third electrode adjacent to the SOC region.

A composite material fabricated using a novel process and materials. The piezoelectric and magnetostrictive layers of the composite material are coated, layered, and bonded using a process known as LTTLP bonding. The resulting magnetoelectric composite fibers are bonded to a polyimide film based copper flexible circuit using a room temperature curing epoxy. The sensor that results is an MEMFC that outperforms conventionally fabricated MEMFCs.

Embodiments of a magnetic field sensor of the present disclosure includes magnetoelectric nanowires suspended above a substrate across electrodes without substrate clamping. This results in enhanced magnetoelectric coupling by reducing substrate clamping when compared to layered thin-film architectures. Accordingly, the magnetoelectric nanowires of the magnetic field sensor generate a voltage response in the presence of a magnetic field.

A power generator 100 includes a power generating unit 10 and a supporting member 20 for supporting the power generating unit 10. The power generating unit 10 constitutes a two-degree-freedom vibration system including a first vibration system having a coil assembly 40 and a first spring portion 64 for coupling the coil assembly 40 with a housing 20 and a second vibration system having a magnet assembly 30 and a second spring portion 65 for coupling the magnet assembly 30 with the coil assembly 40. The power generating unit 10 is configured so that each of a first natural frequency .sub.1 of the first vibration system and a second natural frequency .sub.2 of the second vibration system is in the range of 14 to 42 Hz.