I suppose those are appropriate, albeit limited contexts. It just seems like a strange translation to such a commonly used word in Portuguese to use such a rarely used word in English. I would usually think the "Victorian" period, or the "Antebellum" period; separating historical times.
You do talk about the first, second or third periods talking about parts of the school day or work day. Have a look at the Oxford Advanced Learners Dictionary. Quoting their example: -What do you have on the third period? -French.
Singular (masculine, feminine, neuter)
- this (near the speaker) = este, esta, isto
- that (near the listener) = esse, essa, isso
- that (far from both) = aquele, aquela, aquilo
Plural (masculine, feminine)
- these (near the speaker) = estes, estas
- those (near the listener) = esses, essas
- those (far from both) = aqueles, aquelas
I work on that period means that you are doing research on it. I work in that period suggests that you are at present working at that particular time lapse? Please clarify.