Abstract: A semiconductor memory device includes a cell substrate, a plurality of gate electrodes sequentially stacked on the cell substrate and extending in a first direction, first and second channel structures extending in a second direction different from the first direction and penetrating the plurality of gate electrodes, and a bit line disposed on the plurality of gate electrodes. The first and second channel structures each include a ferroelectric layer, a channel layer, a gate insulating layer and a back gate electrode, which are sequentially disposed on side walls of the plurality of gate electrodes. The first channel structure and the second channel structure are adjacent to each other in the first direction and share a bit line.

Abstract: Provided are a bismuth-based piezoelectric material whose insulation property is improved while its performance as a piezoelectric body is not impaired and a piezoelectric device using the piezoelectric material. The piezoelectric material includes a perovskite-type metal oxide represented by the following general formula (1): Bix(Fe1-yCoy)O3??(1) where 0.95?x?1.25 and 0?y?0.30, and a root mean square roughness Rq (nm) of a surface of the piezoelectric material satisfies a relationship of 0<Rq?25y+2 (0?y?0.30).

Abstract: Provided is a piezoelectric material having a high Curie temperature and satisfactory piezoelectric characteristics, the piezoelectric material being represented by the following general formula (1): A(ZnxTi(1-x))yM(1-y)O3??(1) where A represents a Bi element, M represents at least one element selected from Fe, Al, Sc, Mn, Y, Ga, and Yb; x represents a numerical value of 0.4?x?0.6; and y represents a numerical value of 0.17?y?0.60.

Abstract: Provided is a piezoelectric material having good piezoelectric properties and a Curie temperature (Tc) of 150° C. or higher, and a piezoelectric device using the piezoelectric material. The piezoelectric material includes a sintered body made of a perovskite-type metal oxide represented by the following general formula (1): xBi(Mg1/2Ti1/2)O3-(1-x)BaTiO3 (1), where x satisfies 0.17?x?0.8, in which an average grain size of grains contained in the sintered body is 0.5 ?m or larger to 10 ?m or smaller, and the sintered body is polycrystalline. In addition, the piezoelectric device includes a piezoelectric material and a pair of electrodes disposed in contact with the piezoelectric material, in which the piezoelectric material is the above-mentioned piezoelectric material.

Abstract: Provided is a piezoelectric material which includes a compound free of lead and alkali metal and has a good piezoelectric property. The piezoelectric material where tungsten bronze structure oxides being free of lead and alkali metal and represented by AxB10O30 and A?x?B?10O30 are combined to form a morphotropic phase boundary has good piezoelectric property. The AxB10O30 is b(Ba5?5?Bi10?/3Nb10O30)+(1?b)(Ba4Ag2Nb10O30) (0?b?1 and 0<??0.4), and the A?x?B?10O30 is c(Sr5Nb10O30)+d(Ca5Nb10O30)+e(Ba5Nb10O30) (0?c?0.8, 0?d?0.4, 0.1?e?0.9, and c+d+e=1).

Abstract: Provided are a bismuth-based piezoelectric material whose insulation property is improved while its performance as a piezoelectric body is not impaired, and a piezoelectric device using the piezoelectric material. The piezoelectric material includes a perovskite-type metal oxide represented by the following general formula (1): Bix(Fe1-yCoy)O3??(1) where 0.95?x?1.25 and 0?y?0.30, and a root mean square roughness Rq (nm) of a surface of the piezoelectric material satisfies a relationship of 0<Rq?25y+2 (0?y?0.30).

Abstract: Provided is a piezoelectric material having good piezoelectric properties and a Curie temperature (Tc) of 150° C. or higher, and a piezoelectric device using the piezoelectric material. The piezoelectric material includes a sintered body made of a perovskite-type metal oxide represented by the following general formula (1): xBi(Mg1/2Ti1/2)O3-(1-x)BaTiO3 (1), where x satisfies 0.17?x?0.8, in which an average grain size of grains contained in the sintered body is 0.5 ?m or larger to 10 ?m or smaller, and the sintered body is polycrystalline. In addition, the piezoelectric device includes a piezoelectric material and a pair of electrodes disposed in contact with the piezoelectric material, in which the piezoelectric material is the above-mentioned piezoelectric material.

Abstract: Provided is a piezoelectric material having good piezoelectric properties and a Curie temperature (Tc) of 150° C. or higher, and a piezoelectric device using the piezoelectric material. The piezoelectric material includes a sintered body made of a perovskite-type metal oxide represented by the following general formula (1): xBi(Mg1/2Ti1/2)O3-(1-x)BaTiO3??(1), where x satisfies 0.17?x?0.8, in which an average grain size of grains contained in the sintered body is 0.5 ?m or larger to 10 ?m or smaller, and the sintered body is polycrystalline. In addition, the piezoelectric device includes a piezoelectric material and a pair of electrodes disposed in contact with the piezoelectric material, in which the piezoelectric material is the above-mentioned piezoelectric material.

Abstract: Provided is a piezoelectric material having a high Curie temperature and satisfactory piezoelectric characteristics, the piezoelectric material being represented by the following general formula (1): A(ZnxTi(1-x))yM(1-y)O3??(1) where A represents a Bi element, M represents at least one element selected from Fe, Al, Sc, Mn, Y, Ga, and Yb; x represents a numerical value of 0.4?x?0.6; and y represents a numerical value of 0.17?y?0.60.

Abstract: Provided are a bismuth-based piezoelectric material whose insulation property is improved while its performance as a piezoelectric body is not impaired and a piezoelectric device using the piezoelectric material. The piezoelectric material includes a perovskite-type metal oxide represented by the following general formula (1): Bix(Fe1-yCoy)O3??(1) where 0.95?x?1.25 and 0?y?0.30, and a root mean square roughness Rq (nm) of a surface of the piezoelectric material satisfies a relationship of 0<Rq?25y+2 (0?y?0.30).

Abstract: Provided is a piezoelectric material having a good piezoelectric property and Curie temperature (Tc) of 150° C. or higher, and a piezoelectric device using the piezoelectric material. The piezoelectric material includes a sintered body made of a perovskite-type metal oxide represented by the following general formula (1): xBi(Mg1/2Ti1/2)O3?(1?x)BaTiO3 (1), where x satisfies 0.17?x?0.8, in which an average grain size of grains contained in the sintered body is 0.5 ?m or larger to 10 ?m or smaller, and the sintered body is polycrystal. In addition, the piezoelectric device includes a piezoelectric material and a pair of electrodes disposed in contact with the piezoelectric material, in which the piezoelectric material is the above-mentioned piezoelectric material.

Abstract: Provided is a piezoelectric material which includes a compound free of lead and alkali metal and has a good piezoelectric property. The piezoelectric material where tungsten bronze structure oxides being free of lead and alkali metal and represented by AxB10O30 and A?x?B?10O30 are combined to form a morphotropic phase boundary has good piezoelectric property. The AxB10O30 is b(Ba5?5?Bi10?/3Nb10O30)+(1?b)(Ba4Ag2Nb10O30) (0?b?1 and 0<??0.4), and the A?x?B?10O30 is c(Sr5Nb10O30)+d(Ca5Nb10O30)+e(Ba5Nb10O30) (0?c?0.8, 0?d?0.4, 0.1?e?0.9, and c+d+e=1).