Thermal properties of PZT95/5(1.8Nb) and PSZT ceramics.

Thermal properties of niobium-modified PZT95/5(1.8Nb) and PSZT ceramics used for the ferroelectric power supply have been studied from -100 C to 375 C. Within this temperature range, these materials exhibit ferroelectric-ferroelectric and ferroelectric-paraelectric phase transformations. The thermal expansion coefficient, heat capacity, and thermal diffusivity of different phases were measured. Thermal conductivity and Grueneisen constant were calculated at several selected temperatures between -60 C and 100 C. Results show that thermal properties of these two solid solutions are very similar. Phase transformations in these ceramics possess first order transformation characteristics including thermal hysteresis, transformational strain, and enthalpy change. The thermal strain in the high temperature rhombohedral phase region is extremely anisotropic. The heat capacity for both materials approaches to 3R (or 5.938 cal/(g-mole*K)) near room temperature. The thermal diffusivity and the thermal conductivity are quite low in comparison to common oxide ceramics, and are comparable to amorphous silicate glass. Furthermore, the thermal conductivity of these materials between -60 C and 100 C becomes independent of temperature and is sensitive to the structural phase transformation. These phenomena suggest that the phonon mean free path governing the thermal conductivity in this temperature range is limited by the lattice dimensions, which is in good agreement with calculated values. Effects of small compositional changes and density/porosity variations in these ceramics on their thermal properties are also discussed. The implications of these transformation characteristics and unusual thermal properties are important in guiding processing and handling procedures for these materials

Upaya Mengurangi Bullying Anak Usia Sekolah Dasar Melalui Kegiatan Sosialisasi

Tujuan dari kegiatan ini adalah untuk meningkatkan pengetahuan dan pemahaman anak-anak usia sekolah dasar mengenai bullying pada anak di SDN Negeri Wakarleli dengan mengadakan Sosialisasi Pencegahan Bullying pada Anak. Sosialisasi ini merupakan salah satu alternatif yang dapat dilakukan sebagai upaya mencegah dan mengurangi perilaku bullying pada anak usia sekolah terhadap teman sebayanya. Kegiatan pengabdian pada masyarakat ini melibatkan lembaga pendidikan yaitu Sekolah Dasar Negeri Wakerleli sebagai mitra yaitu 8 orang guru dan 120 orang peserta didik secara keseluruhan, serta tim dari mahasiswa KKN Desa Wakarleli. Hasil dari kegiatan pengabdian pada masyarakat ini yakni meningkatnya pengetahuan dan pemahaman anak terhadap tindakan bullying yaitu sebanyak 45 anak dari total keseluruhan 120 anak berada pada kategori sangat tahu. Pengetahuan yang didapatkan berupa pengertian bullying, jenis-jenis bullying, dampak bullying bagi korban, pencegahan bullying oleh siswa, pencegahan bullying oleh masyarakat, dan pencegahan bullying oleh sekolah