16 results about "Wurtzite crystal structure" patented technology

A device includes a substrate, a ferroelectric structure supported by the substrate, the ferroelectric structure having a wurtzite crystal structure, a switchable conduction path in the ferroelectric structure, the switchable conduction path being disposed along a lateral domain all in the ferroelectric structure, the lateral domain wall defining a first portion of the ferroelectric structure and a second portion of the ferroelectric structure having a first polarity and a second polarity, respectively, and an electrode disposed relative to the ferroelectric structure such that a voltage applied to the electrode establishes or removes the lateral domain wall and the switchable conduction path in the ferroelectric structure.

A method for searching for ferroelectric materials, such as wurtzite crystal structures, that have low coercive fields and high spontaneous polarization values ​​using first-principles calculations is provided. [Solution] The method includes a first extraction step of obtaining, from a crystal structure database, ferroelectric material candidates with non-centrosymmetric symmetry as first candidates; a calculation step of calculating the band gap value, polarization reversal barrier energy value, and spontaneous polarization value of each first candidate obtained in the first extraction step using first-principles calculations; an insulating property determination step of determining whether the calculated band gap value satisfies insulating properties; a polarization reversal determination step of determining whether the calculated polarization reversal barrier energy value is within a range in which polarization reversal is possible; a spontaneous polarization determination step of determining whether the calculated spontaneous polarization value is within a range in which ferroelectric properties are exhibited; and a second extraction step of extracting, as ferroelectric materials, first candidates for which the determination results in the insulating property determination step, polarization reversal determination step, and spontaneous polarization determination step are all acceptable.

The purpose of the present invention is to provide: a piezoelectric element which does not have a buffer layer, has sufficient piezoelectric characteristics and stability, and can be further reduced in size compared to conventional piezoelectric elements; and a MEMS device which uses the piezoelectric element. This piezoelectric element is provided with: a piezoelectric layer (10) comprising a nitride material having a wurtzite crystal structure; a first electrode (20) provided on one surface of the piezoelectric layer; a second electrode (30) provided on the other surface of the piezoelectric layer; the first electrode has a wurtzite-type crystal structure and is made of a first nitride material having a resistivity of 1.0 * 10 <-3 > [Omega] cm or less. The second electrode has a wurtzite-type crystal structure and is made of a second nitride material having a resistivity of 1.0 * 10 <-3 > [Omega] cm or less.

The application discloses a PHI / zinc oxide heterojunction photocatalyst and a low-temperature synthesis method and application thereof. The structure of the photocatalyst is that PHI nanosheets grow well on the surface of ZnO and are tightly wrapped with ZnO, forming a sheet-shaped core layer structure, the thickness of the PHI nanosheet is 3-5 nm, and the ZnO is a wurtzite crystal structure. The low-temperature synthesis method comprises the following steps: mixing and heating a PHI precursor and a molten salt to obtain PHI, placing the PHI and a zinc oxide precursor in an aqueous solution, adding an alkali to adjust the pH, and then reacting to obtain the photocatalyst PHI / ZnO. The photocatalyst can be used for activating molecular oxygen to oxidize the C-H bond at the benzyl position of CM to prepare cumene hydroperoxide, and can also be used for a cascade oxidation reaction to form imine and sulfoxide series compounds. The application shows the advantages of the high-activity carbon nitride-based photocatalyst in the field of organic conversion, and provides an important platform for realizing the essence safety, green and efficient oxidation reaction by the peroxide strategy.

The invention relates to a super-long aluminum nitride single-crystal nanofiber material and a preparation method and application thereof, the preparation method comprises the following steps: 1) performing vortex rotary spray granulation on an aluminum source, a series catalyst, an oxidation inhibitor and a binder to obtain precursor particles; 2) carrying out negative pressure suction on the precursor particles to enable the precursor particles to be uniformly distributed on the pore channel type reaction substrate to obtain a pre-reaction substrate; 3) carrying out alternating temperature calcination on the pre-reaction substrate to obtain an ultra-long nanofiber crude product; and (4) carrying out high-temperature substrate removal, ultrasonic cleaning and drying treatment on the super-long nanofibers to finally obtain the super-long aluminum nitride single-crystal nanofiber material. Compared with the prior art, the material is composed of a large number of aluminum nitride nanofibers with the diameter of 100-600 nm, the length reaching the centimeter level and the length-diameter ratio larger than 10000 and has the advantages that the high-purity wurtzite crystal structure is achieved, the fibers are soft and can be bent and recovered at any angle, the unit yield is high, and the application field of the aluminum nitride material is greatly widened.

The utility model discloses a high-performance storage device structure using AlScN ferroelectric material, comprising a substrate layer, an insulating layer, a ferroelectric layer, a polarization buffer layer and a grid layer which are arranged in sequence from bottom to top, the ferroelectric layer adopts an AlScN film, the thickness of the ferroelectric layer is 20nm, and the polarization buffer layer adopts AlN, and the thickness of the polarization buffer layer is 10nm. The utility model provides a high-performance storage device structure using an AlScN ferroelectric material, AlScN has a wurtzite crystal structure, is stable in ferroelectricity, can keep a specific electric state after an external electric field is removed, can keep stable in an environment as high as 1100 DEG C, is an ideal material for realizing non-volatile storage, and can be used as a high-performance storage device. AlScN has the lowest dielectric constant in the inorganic ferroelectric material, and is beneficial to increasing the sensing margin of the FeRAM; the AlScN thin film can grow at the temperature lower than 400 DEG C by using a magnetron sputtering technology, is compatible with a CMOS (Complementary Metal Oxide Semiconductor) manufacturing process, does not contain volatile elements, and reduces the pollution risk in the COMS (Complementary Metal Oxide Semiconductor) process.

The present invention relates to a coated cutting tool consisting of a substrate body and a coating, the substrate being cemented carbide and the coating comprising a first cubic metal nitride layer and a 10 to 500 nm thick Al 1‑v‑y‑z M v Si y X z N layer below the first cubic metal nitride layer, wherein 0 < v < 0.75, 0 < y < 0.20, 0 < z < 0.10, wherein the Al 1‑v‑y‑ z M v Si y X z N layer has a wurtzite crystal structure. 1‑v‑y‑z M v Si y X z N layer has a wurtzite crystal structure.

This invention discloses a doped aluminum nitride ferroelectric thin film, a ferroelectric device, and its fabrication method. The doped aluminum nitride ferroelectric thin film has a wurtzite crystal structure and forms an atomic layer structure with periodically modulated doping concentration along the polarization axis [0001]. This structure is composed of alternating stacks of highly doped and low-doped atomic sublayers, with a period length as small as one unit cell length. The vertical spacing between cation and anion layers in different sublayers varies, thus introducing localized polarization differences at the atomic scale. By controlling the sputtering parameters, a periodic distribution of doping elements along the film thickness direction can be achieved. Under external electric field or electron beam excitation, the thin film exhibits non-collective step-like polarization reversal dynamics, which is beneficial for reducing the polarization reversal energy barrier and improving ferroelectric switching performance. This invention also provides a ferroelectric device based on this thin film and its fabrication method, which has good process compatibility and application prospects.

The invention provides a preparation method and application of a piezoelectric sensor vibration device based on an h-BN / GaN heterojunction, and belongs to the technical field of piezoelectric sensors, a third-generation semiconductor material gallium nitride is used as a core material of a novel piezoelectric sensor, and the piezoelectric sensor vibration device based on the h-BN / GaN heterojunction is prepared by using piezoelectric characteristics determined by inherent asymmetry of a GaN wurtzite crystal structure. The problem of heat temperature failure caused by Curie temperature limitation of conventional piezoelectric materials such as piezoelectric ceramics is solved, and meanwhile, the technical problems that a traditional piezoelectric sensor is narrow in frequency response range, poor in temperature stability and slow in dynamic response are solved by utilizing the characteristics of high forbidden bandwidth, high electron mobility and high temperature resistance of GaN. On the basis of a GaN material, an h-BN / GaN heterostructure is constructed by means of hexagonal boron nitride (h-BN), the piezoelectric effect of a strain engineering and interface collaborative polarization enhancement device is utilized, the technical problem that the piezoelectric coefficient is low when GaN is singly used for preparing a piezoelectric sensor is solved, meanwhile, the two-dimensional structural characteristic of the h-BN is utilized, the flexible piezoelectric detector can be prepared in cooperation with the GaN, and the flexible piezoelectric sensor has the advantages of being simple in structure, low in cost and the like. And light-weight and thin-film device design is realized.

A radiator includes a heat radiation ceramic material. The heat radiation ceramic material includes a first metal oxide as a principal component, the first metal oxide being a metal oxide having a wurtzite crystal structure; and a second metal oxide as a metal oxide having an average emissivity higher than or equal to 70% in a wavelength range of 3 μm to 25 μm inclusive. At least one of a trivalent metal-doped metal oxide where some metal atoms of the first metal oxide are substituted with trivalent metal atoms and a monovalent metal-doped metal oxide where some metal atoms of the first metal oxide are substituted with monovalent metal atoms is included as the second metal oxide.

A piezoelectric device having a high conversion efficiency between electrical energy and mechanical energy is provided. The piezoelectric device has first electrode, a second electrode, and a piezoelectric layer provided between the first electrode and the second electrode, wherein the piezoelectric layer is formed of a ZnO-based material having a wurtzite crystal structure to which a metal that does not cause the piezoelectric layer to exhibit conductivity is added, and wherein a squared value of a electromechanical coupling coefficient in thickness vibration mode is 6.5% or more.

The invention provides a BAW resonator which can reduce wiring resistance and exert energy limiting effect. The BAW resonator (1) according to the present invention is provided with a support substrate (10), an acoustic mirror layer (20) in which one or more pairs of high acoustic impedance layers (21) and low acoustic impedance layers (22) are alternately laminated, a first electrode (40), a piezoelectric layer (50) having a wurtzite crystal structure, and a second electrode (60) are laminated in this order, and has an intermediate layer (30) that is provided between the acoustic mirror layer (20) and the first electrode (40) and contains an insulator. The intermediate layer (30) has a higher acoustic impedance than the low acoustic impedance layer (22), and the first electrode (40) has a lower acoustic impedance than the high acoustic impedance layer (21).

[Problem] The purpose of the present invention is to provide: a piezoelectric element which does not have a buffer layer, has sufficient piezoelectric characteristics and stability, and can be further reduced in size as compared with conventional piezoelectric elements; and a MEMS device which uses the piezoelectric element. [Solution] The present invention comprises: a piezoelectric layer 10 that is formed of a nitride material which has a wurtzite crystal structure; a first electrode 20 that is provided on one surface of the piezoelectric layer; and a second electrode 30 that is provided on the other surface of the piezoelectric layer. The first electrode is formed of a first nitride material that has a wurtzite crystal structure and an electrical resistivity of 1.0 × 10-3 Ω∙cm or less. The second electrode is formed of a second nitride material that has a wurtzite crystal structure and an electrical resistivity of 1.0 × 10-3 Ω∙cm or less.

This invention discloses a quantum dot with oriented luminescence, comprising: a core; and a shell covering the outer surface of the core. The core includes a wurtzite crystal structure, and the shell includes both a wurtzite crystal structure and a zincblende crystal structure, such that the quantum dot's crystal structure forms a polymorphic crystal structure along the c-axis of the wurtzite crystal. The polymorphic crystal structure includes two layers of zincblende crystal structure and a wurtzite crystal structure located between the two layers of zincblende crystal structure. By forming the quantum dot with a polymorphic crystal structure along the c-axis of the wurtzite crystal, the orientation of the quantum dot's transition dipole moment is controlled, thereby controlling the orientation of the quantum dot's luminescence. This invention also discloses a quantum dot thin film prepared using the above-mentioned quantum dot. The dipole-dipole interactions between the quantum dots cause the c-axis of the wurtzite crystals of the quantum dots to be antiparallel to each other and perpendicular to the substrate, making the preferred orientation of the quantum dot thin film's transition dipole moment parallel to the substrate.

[Problem] The purpose of the present invention is to provide: a piezoelectric element which does not have a buffer layer, has sufficient piezoelectric characteristics and stability, and can be further reduced in size as compared with conventional piezoelectric elements; and a MEMS device which uses the piezoelectric element. [Solution] The present invention comprises: a piezoelectric layer 10 that is formed of a nitride material which has a wurtzite crystal structure; a first electrode 20 that is provided on one surface of the piezoelectric layer; and a second electrode 30 that is provided on the other surface of the piezoelectric layer. The first electrode is formed of a first nitride material that has a wurtzite crystal structure and an electrical resistivity of 1.0 × 10-3 Ω∙cm or less. The second electrode is formed of a second nitride material that has a wurtzite crystal structure and an electrical resistivity of 1.0 × 10-3 Ω∙cm or less.

Single-phase manganese oxide particles having a wurtzite crystal structure. The particles can be obtained by thermally decomposing a compound containing manganese. In this procedure, a reducing agent consisting of at least one of a polyol-based material and an ethylene glycol stearate-based material is added as an additive to the reaction system. It is heated at a first temperature (200° C. or lower) under a reduced pressure atmosphere, then the temperature is raised, and the product is heated at a temperature higher than the first temperature under an inert gas atmosphere.