Abstract: A semiconductive ceramic member according to the present disclosure contains a plurality of aluminum oxide crystal grains, and a plurality of titanium oxide crystal grains. The total content of aluminum oxide and titanium oxide is 99% by mass or more per 100% by mass of all constituents. The content of the aluminum oxide is 86% by mass or more and 96% by mass or less and the content of the titanium oxide is 4% by mass or more and 14% by mass or less per 100% by mass of the aluminum oxide and the titanium oxide in total. A peak of TiOx (0<x<2) is present within a binding energy range of 456 eV to 462 eV (both inclusive) in X-ray photoelectron spectroscopy measurement. The semiconductive ceramic member further contains silicon, and the content of the silicon in terms of its oxide in a first region is larger than the content of the silicon in terms of its oxide in a grain boundary.

Abstract: A semiconductive ceramic member includes alumina ceramics containing ?-alumina and titanium oxide. The alumina ceramics contains a content of 89-95% by mass of Al in terms of Al2O3, and a content of 5-11% by mass of Ti in terms of TiO2. When a total content of Al in terms of Al2O3 and Ti in terms of TiO2 is taken as 100 parts by mass, the alumina ceramics contains a content of 0.02-0.6 part by mass in total of Ca in terms of CaO and Ce in terms of CeO2 relative to the 100 parts by mass. The member has a bulk density of 3.7 g/cm3 or more and a peak of TiOx (0<x<2) within a binding energy range of 456-462 eV in X-ray photoelectron spectroscopy. A surface of the member has a lightness index L* of 40 to 60, and ?L* of 1 or less.

Abstract: A layered unit provided with piezoelectric ceramics having an increased adhesive strength while lowering cell content in an adhesive layer, a method for producing the layered unit, and an ink jet printing head incorporated with such layered unit having improved ink emission precision and durability as well as suppressing occurrence of assembly failure at the time of producing the ink jet printing head. The layered unit has a first member made of piezoelectric ceramics, a second member which is placed over the first member, and an adhesive layer which is formed between the first member and the second member to adhere the first member and the second member. A joint surface of the first member to be jointed to the second member is formed with a multitude of recesses. A sum of opening areas of the recesses occupies 50% or more relative to a total surface area of the joint surface of the first member.

Abstract: Provided are a layered unit provided with piezoelectric ceramics having an increased adhesive strength while lowering cell content in an adhesive layer, a method for producing the layered unit, and an ink jet printing head incorporated with such layered unit having improved ink emission precision and durability as well as suppressing occurrence of assembly failure at the time of producing the ink jet printing head. The layered unit has a first member made of piezoelectric ceramics, a second member which is placed over the first member, and an adhesive layer which is formed between the first member and the second member to adhere the first member and the second member. A joint surface of the first member to be jointed to the second member is formed with a multitude of recesses. A sum of opening areas of the recesses occupies 50% or more relative to a total surface area of the joint surface of the first member.