I've read a few days ago that by precipitation of an aqueous solution of a cobalt(II) salt with urea at 85oC for 2 hours you can obtain cobalt(II) carbonate. You can find the paper at this link: http://www.ncbi.nlm.nih.gov/pubmed/15350915.
Hi.Michael Päch,Thank you for answering , but is cobalt (II) ion in aqueous solution not stable. do you mean that cobalt carbonate(II) in solution(or dried) is oxide?Rose is a divine gift. Thanks