Preparation And Properties Of Calcium-doped Barium Titanate Nano-powders By Hydrothermal Method

Barium titanate is the most widely used material in electronic ceramics and is known as"the pillar of the electronic ceramics industry".With the development of 5G technology and new energy vehicles in recent years,higher requirements have been placed on the upper limit of working temperature and high temperature stability of barium titanate materials.Calcium-doped barium titanate can just solve these problems.Due to the large particle size of the calcium-doped barium titanate powder prepared by the solid-phase method,it is difficult to meet the requirements for miniaturization and high performance of electronic components.Therefore,many scholars have devoted themselves to the research of the liquid-phase method.In this paper,the preparation of calcium-doped barium titanate nano-powders was studied by hydrothermal method,and the effect of calcium doping on barium titanate ceramics and its dielectric properties was explored.The samples were characterized by XRD,SEM,LCR and other methods.The main research work and results are as follows:（1）Using BaCl₂·H₂O,CaCl₂and highly active and inexpensive H₂Ti O₃as raw materials,and KOH as mineralizer,barium titanate and calcium titanate nanopowders with basically the same particle size were prepared by hydrothermal method.The hydrothermal synthesis rule of calcium titanate nano-powder,combined with the preparation parameters of the two,optimized the preparation process,prepared calcium-barium titanate nano-powder,and explored different reaction conditions such as reaction temperature,reaction time,mineralizer concentration,etc.Effects on powder preparation.The results show that when the hydrothermal reaction conditions are taken at a temperature of 210°C,a mineralizer concentration of 3 mol/L,and a reaction time of 22 h,the prepared calcium-barium titanate nano-powders have good crystallinity,complete and uniform grain development.Dispersion and fine particle size（110±20 nm）.（2）The barium titanate nano-powders were doped with calcium from macroscopic and microscopic perspectives.The first calcium-doped barium titanate was prepared by mixing the barium titanate and calcium titanate nanopowders prepared by hydrothermal method in a certain proportion;the second is calcium barium titanate nano powder prepared by hydrothermal.Two kinds of doped powders were made into ceramics,and the effects of calcium doping on barium titanate ceramics and their dielectric properties were investigated.The results show that at a heating rate of 5℃/min,the debonding is kept at600℃for 4 h,and the sintering at 1250℃for 2 h can obtain dense crystals with an average grain size of about 1μm,which is in line with the grain size of barium titanate.effect optimized conditions for ceramics.With the increase of calcium doping content,the dielectric Curie peaks of the ceramics prepared by the two kinds of doped powders shifted to the high temperature direction,broadened and decreased,and reached the maximum when the doping ratio was 9%.At this time,the Curie temperature of the ceramic prepared from the first doped powder is 139.2°C,and the dielectric constant and dielectric loss at room temperature are 2343 and 0.0259,respectively;the second Curie temperature is136.2°C,normal temperature The dielectric constant and dielectric loss were 1852 and0.0197,respectively.The doping of calcium increases the Curie temperature of barium titanate and improves the temperature characteristics of barium titanate.