公开(公告)号：JPH06318432A

公开(公告)日：1994-11-15

申请号：JP10803793

申请日：1993-05-10

Applicant: MATSUSHITA ELECTRONICS CORP

Inventor： OZAWA TETSUO ,  ONISHI SUSUMU ,  INAGUMA KUNIO ,  MASUDA MUTSUO

IPC: C01F11/18 ,  H01J1/14 ,  H01J9/04

Abstract: PURPOSE:To surely synthesize needle crystal carbonate having a length ratio of a longer axis to a shorter axis of crystals within a specific range, having uniform characterics as an electron tube cathode, and having an excellent emission life by setting the pH value of mixed solution of nitrate below in a specific value synthesizing reaction of the carbonate for the electron tube cathode. CONSTITUTION:Barium nitrate and strontium nitrate are dissolved in pure water to form mixed solution (A) of nitrate of the same specific concentration. Next, sodium carbonate is dissolved in pure water so as to form sodium carbonate solution (B) of a specific conceutration. The liquid (A) is agitated, and the liquid (B) is added gradually while liquid temperature is kept constant, so carbonate including barium and strontium is produced by (Ba, Sr)(No3)2+Na2 CO3 (Ba, Sr)CO3+2NaNO3. As the liquid (B) is added, a pH value increases from its initial value. When the pH value become 9, addition of the liquid (B) is stopped. In this method, needle crystal carbonate having a length ratio of a long axis to a short axis within a range of 4:1-20:1 is obtained.

公开(公告)号：JPH06329413A

公开(公告)日：1994-11-29

申请号：JP12129593

申请日：1993-05-24

Applicant: MATSUSHITA ELECTRONICS CORP

Inventor： ONISHI SUSUMU ,  OZAWA TETSUO ,  INAGUMA KUNIO ,  MASUDA MUTSUO

IPC: C01F11/18 ,  H01J1/14 ,  H01J9/04

Abstract: PURPOSE:To produce a carbonate excellent in emission life properties as a cathode of an electronic tube by surely, easily and steadily preparing a large needle-shaped carbonate crystal at a low cost. CONSTITUTION:An aqueous solution of nitrate salts of an alkaline earth metal mixture mainly containing barium is mixed and reacted with a carbonate ion- containing aqueous solution to precipitate carbonate salts of the alkaline earth metal mixture mainly containing barium. In this process, a needle-shaped carbonate crystal having the length of main crystal axis in the range of 2-10mum is obtained by using an aqueous solution of sodium hydrogencarbonate as the carbonate ion-containing aqueous solution.