The pellets were sintered in a special regime with maximal temperature T s = 1,300°C for 5 h. Temperature-sensitive Cu0.1Ni0.1Co1.6Mn1.2O4/Cu0.1Ni0.8Co0.2Mn1.9O4-based pastes were prepared by mixing powders of basic ceramics (72.8% of sintered bulk ceramics were preliminarily destroyed, wet-milled, and dried) with ecological glass powders (2.9%) without PbO, inorganic binder Bi2O3 (2.9%), and organic vehicle (21.4%). The next content was used for the preparation of humidity-sensitive thick-film pastes: MgAl2O4-based ceramics (58%), Bi2O3 (4%), ecological glass (8%), and organic vehicle (30%). The pastes were printed on alumina substrates (Rubalit 708S, CeramTec, Plochingen,
Germany) using a manual screen printing device equipped with Ganetespib purchase a steel screen. Then, thick films were sintered in PEO-601-084 furnace at 850°C [20, 23]. The insulating (i-type) paste in two layers was printed on temperature-sensitive Dasatinib datasheet (p-type) thick-film layer previously formed on alumina substrate. In contrast to previous works [21, 23], the p+-conductive paste was formed on humidity-sensitive i-type layer as conductive layer. Then, these structures were sintered in the furnace. The topological scheme of integrated
p-i-p+ thick-film structure is shown in Figure 1. Figure 1 Topological scheme of integrated thick-film p-i-p + structure. The microstructure of the sintered temperature-sensitive ceramics was probed using an electron microscope JSM-6700 F (JEOL Ltd., Akishima, Tokyo, Japan), cross-sectional morphology of the samples being tested near the surface (0- to 70-μm depth) and chip centers. Scanning electron microscopy (SEM) investigations for bulk humidity-sensitive ceramics and thick-film structures were performed using
LEO 982 field emission microscope (Carl Zeiss AG, Oberkochen, Germany). The pore size distribution of bulk semiconductor and dielectric ceramics in the region from 2 to 1,000 nm was studied using Hg-porosimetry (POROSIMETR Casein kinase 1 4000, CARLO ERBA STRUMENTAZIONE, Hofheim am Taunus, Germany). The electrical resistance of thermistor thick films was measured using temperature chambers MINI SUBZERO, Tabai ESPEC Corp., Japan, model MC-71 and HPS 222. The humidity sensitivity of thick-film structures was determined by measuring the dependence of electrical resistance R on relative humidity (RH) of the environment. The electrical resistance was measured in the heat and humidity chamber PR-3E (Tabai, Osaka, Japan) at 20°C in the region of RH = 20% to 99%. The electrodes were attached to connecting cables of M-ohmmeter at fixed current frequency of 500 Hz (with the aim of avoidance of polarization of adsorbed water molecules). In addition, the degradation transformation at 40°С and RH = 95% for 240 h was carried out in order to study sample stability in time. The maximal overall uncertainties in the electrical measurements did not exceed approximately ± (0.02 to 0.