To remind people, this is what the Imperial Government of Russia had to say on the subject:
The title of the Russian Monarch is Emperor and Imperial Majesty. Originally the Russian Sovereigns bore the title of grand dukes. With the uniting of Russia under the dominion of Moscow, the title of Tsar began to be used, and was, definitely adopted by Ivan IV in 1547. This remained the title of the Russian Sovereigns unil 1721. In 1721, by the peace of Nishtadt, the Great Northern war, carried on so successfully by Peter the Great, was concluded. In celebration of this event, the Senat and Synod resolved t beg Peter I to accept the titles of Emperor, Great, and Father of his Country. A supreme Ukas was issued to that effect, on November 11, 1721, which gave rise to a protest on the part of many European states, as it placed the Russian Sovereign on the same level with the Emperor of Germany, the sole Monarch of that rank then existing. First to acknowledge the new title were Prussia, the Netherlands and Sweden, last - Poland in 1764.
- Statesman's Handbook for Russia
1896 - By the Chancery of the Committee of Ministers, St. Petersburg